The present invention relates generally to hydraulic valves, and more particularly, to a new and improved hydraulic sequencing valve.
Many modern hydraulic circuits include elements which must be operated in a sequential or cyclic manner. For example, hydraulic circuits used in refuse compactors must operate so as to extend a ram and compact the refuse material. When the ram reaches the end of its stroke, the hydraulic circuit automatically operates so as to reverse the direction of ram travel and return the ram to its original or start position. In other machines and circuits, hydraulically powered motors are operated to provide a motion in a given direction, and thereafter in a reverse direction and to return related machine elements to an original or start position. Machine operation is then halted.
One specific application for such a hydraulic sequencing valve is in a roll-over plow system. In such a system, it is necessary for the plow to be rolled or turned over in between succeeding rows. The hydraulic sequencing valve to be described hereinafter is particularly adapted for use in such a system.
It is therefore a general object of the present invention to provide an improved hydraulic sequencing valve.
It is a more particular object of the present invention to provide a hydraulic sequencing valve which includes an internal valve spool which is movable between first and second positions for sequencing the operation of the valve and wherein means are provided for accelerating the sequencing motion of the internal valve spool.
It is a further object of the present invention to provide such a hydraulic sequencing valve wherein the internal spool defines with the body of the valve fluid flow paths between a pair of line ports and tank and pump ports and wherein the spool and valve body further define a direct fluid path between one side of the spool and the tank port for creating a pressure differential between internal chambers of the spool upon initial sequencing movement of the spool to positively accelerate the sequencing motion of the spool.
It is also a further object of the present invention to provide such a hydraulic sequencing valve which includes a counterbalance valve for continuously metering the flow of fluid from the valve in one operating mode.